\makeatletter
\usepackage{wallpaper}
\renewcommand*{\maketitle}{%
\setkeys{Gin}{width=\paperwidth,height=\paperheight,keepaspectratio}
\begin{titlepage}
  \thispagestyle{empty}
  \noindent\fboxsep=0pt
  \ThisTileWallPaper{\paperwidth}{\paperheight}{../../templates/book/ctexbook/images/53.png}
	\vspace{.18\textheight}
	\begin{center}
		{\Huge\bfseries\@title\par}
	\vspace{1cm}
		{\ifdefined\@subtitle{\Large\@subtitle}\fi\par}
	\vspace{2.5cm}
		\@author
	\vfill\centering{build with pandoc \par \today\par}
		\vspace{.05\textheight}
	\end{center}
\end{titlepage}
}
%\setkeys{Gin}{width=\maxwidth,height=\maxheight,keepaspectratio}
\makeatother